Reply to HJ's Question: Are there any compounds with quadriplet bond?

Hj: ms pang,is there such thing as quadriplet bond?

my reply: Should not have at your level. The maximum number of bonds between two atoms is only triple bond. eg:

dot and cross structure of nitrogen molecule

Structural formula ( read as ' N triple bond N ' )

As for the presences of quadruple bond... yes.... mainly in transition metal. Eg: Chromium.

I double check with miss wendy heng regarding HJ's question and I almost forgotten that in uni, we did manage to draw quadruple bond!!! ( many thanks to her ).

Just for your information... not in your secondary syllabus.....

chromium acetate

I edited this diagram so that you can see the quadruple bond easier... the original diagram is blur and show 5 bonds due to low resolutions.

I didnt draw these structures, i got it from this website:

(1) http://www.gcsescience.com/a25.htm ( nirogen molecule )

(2) wwwchem.uwimona.edu.jm:1104/courses/chromium.html ( chromium acetate )

p/s: is KING = Gareth? .. i assume HJ as 'hong jie'

ms pang :)

Chemistry Remedial For 4E1/4 Sci-Chemistry and 3E2 Pure Chemistry

Dear 4E1/4 and 3E2

In view of the upcoming MYE ( mid year exam )2008. There will be remedials for these days:

4E1/4 ( 3e2, be patient. Your timeslot is written below 4E .. so read on)

Our remedial will resumes from this saturday ( 26 april 08 ) onwards. Reason for cancelling the remedial on 19 april is due to real busy day of mine from morning.

The remedial will be conducted at only 1 slot: 10 am till 11.30am at AVA.

Target audience... 60 pax of you.

Topic: Chemical Analysis ( Cation/Anion)

This is a SUPER difficult and important topic ; this topic worths at least [5 mks ] in exam EVER YEAR without fail.

Since this topic needs alot of practice... we will continue with more practise for chemical analysis on 3 May 08. Same time, same venue.

You are advise to turn up for both sessions so you can have maximum exposure to this topic. Should you choose to attend only 1 of the above sessions, you may feel lost as practise is a continuation process.

3E2

Please inform your parents you have remedial.

Session 1- Revision: Structure of Atoms & Bonding ( 26 april 08 / 8.30-9.30/AVA )

Session 2- Revision: Formulas & Balancing Equation ( 3 may 08 / 8.30-9.30/AVA )

I will be going through FYS on 30 April. So all of you please stay back after your last paper. Have your lunch before our revision.

For administration purpose and monitoring of results, these are the pupils who attend sat remedial:

22 march 08

anas, michael, jason, yazid, cheryl, natasha, cheng hong, ronald

29 march 08

jessica, weifen, jolene, farid, anas, michael, jason, cheng hong, natasha, cheryl, jeffery

05 march 08

farid, jeffery, cheng hong, david, michael, anas, meiling, jolene, natasha, cheryl, jia min, yan ne, pei yee, weifen

__________________________________________________

The preparation for O-Level Exam is similarly to preparing for a Marathon.....

Before you run, you need to warm up. However, with 'conditioning your body' for the run, it is impossible to have a marathon because it may lead to sprains and you may not even complete the run!!!

Slow and steady wins the race.

cheers,

ms pang:)

Reply To Mark's Question: Why must we have UV light for free radical substitution.

My reply:

Firstly to have chlorine radical, i need to get it from chlorine molecule....

So, I need a minimum energy to break up my chlorine molecule to get chlorine radical....

ms pang :)

Reply To Mark's Question: Nobel Gases Group 8 or Group 18

Mark asked: ms pang, why is it we learn that nobel gas are grp 8 metals when they are grup 18? source: http://en.wikipedia.org/wiki/Noble_gases

my reply:

Indeed an interesting question!!!

But, let me make an amendment to your question...

Noble Gases are group X or group 0 non-metals.... not METALS.

Anyway, why wikipedia says group 18?

This is a new TERMINOLOGY....

Most scientist wanted to fit Transitions Metal into groups too... recall in our periodic table, transition metals are catagorise as a 'rectangular block' with no group......

So, after adding the transitions metal, we will have 18 groups hence noble gases become group 18!!!

Nonetheless, facts from websites cannot be trusted wholesomely..... unless it is some education (edu) or government (gov) websites..... such websites have more credibility.

ms pang :)

Reply To Hao Eng's Question: Does SO2 have double bonds?

Hao Eng asked: Does SO2 have double bonds between them?

My reply: Yes!

Both sulphur and oxygen has 6 electrons in their outermost shell. In order to have 8 electrons for oxygen atoms (octet structure ), sulphur needs to share 2 electrons with EACH oxygen.

Alas, then sulphur will have 10 electrons!!! Which is not octet structure!

In tertiary levels ( jc/poly/uni), sulphur can 'expand octet' which is a term refering to an atom that has more than 8 electrons in its outermost shell ...

A piece of good news. You are not expected to draw this structure for O-level Exam.....

ms pang :)

p/s: i didnt draw this diagram, i got it from this website:

http://www.btinternet.com/~chemistry.diagrams/molecular_diagrams.htm

Reply To Qi Ying's Question: How many bonds does chlorine and hydrogen have?

Qi Ying asked: how many bonds does chlorine and hydrogen have?

my reply:

Chlorine and hydrogen does not have bonds. The question 'should be' how many electrons can the hydrogen and chlorine used for bonding.

Chlorine is in Group 7 so it has 7 electrons.
If it combines with a metal group, then it can only accept 1 electron from the metal. ( so that add up to be 8 electrons )

If it combines with a non-metal group, then it can share only 1 electron from the non-metal thus forming 8 electrons too.

In this case, if chlorine combines with hydrogen to form hydrogen chloride, then only 1 bond is formed between hydrogen and chlorine.

ms pang :)